Integrated circuits are manufactured from semiconductor substrates, or wafers, on which transistors, resistors, diodes and other electrical circuit elements are formed. The production of integrated circuits involves a multitude of processing procedures performed on semiconductor wafers. One such process whereby ions are implanted on semiconductor wafers is the reactive ion etch (RIE) process. It is quite important in semiconductor manufacturing that particulates formed upon a semiconductor within one manufacturing process be completely removed prior to a subsequent manufacturing process. Traditionally, the wafers are cleaned and rinsed prior to and subsequent to each procedure. Cleaning and rinsing is required in order to stop the chemical reaction that occurs during etching and to remove the etchant chemical or other contaminant matter from the wafer surface. The complete removal of particulate residue from semiconductor substrates will enhance the functionality and reliability of the completed integrated circuits.
Methods by which wafers may be rinsed with deionized water are common to the art. These methods include static water overflow baths, quick dump rinse (QDR) baths and processes whereby additional energy is introduced to the bath through ultrasonic or megasonic agitation. Another method involves bubbling air or gas from the bottom of the tank across the surface of the wafers and relying on convection currents to agitate the water molecules and facilitate water molecule interaction with the face of the wafer. A recent study has indicated that as little as 20% of the water within such tanks makes contact with the wafers.
Additionally, the traditional cleaning and rinsing methods do not adequately remove particulate matter from the tank itself. When particulate contaminates and etching chemicals have bonded with deionized water molecules during removal from the surface of a wafer or substrate, they tend to cling to the sides and corners of the associated rinse tank. This is particularly true of QDR tanks.
Furthermore, as the size of semiconductor wafers increases, water consumption in rinsing and cleaning steps has increased exponentially. Larger wafers require larger tanks which tend to waste additional deionized water. Traditional cleaning and rinsing methods are often inefficient, consume too much deionized water, and waste time.